Positioning apparatus is well known for use in causing controlled movement of various devices, and such apparatus is now commonly used, for example, for causing controlled movement of the magnetic heads of recording devices.
Floppy disk magnetic recording devices commonly include a head carriage having upper and lower magnetic heads mounted thereon which cooperate with recording tracks on the upper and lower magnetic recording surfaces of a removable floppy disk. Such disks now in common use are 51/4 inch and 31/2 inch diameter disks having circular, concentric tracks thereon with now popular track formats being 48 and 96 tracks per radial inch (TPI).
When the disk is in operating position within the recording device, it is known that the head carriage can be moved to cause movement of the head, or heads, along a radius of the rotating disk to thereby locate each head at a desired track so that the device can transduce the information thereat (i.e., either write information onto the disk on the desired track or read information stored thereat).
To effect a desired positioning of the heads, it is also known that command pulses can be provided to initiate the desired head movement, and such movement can be thereafter effected by an electric motor, such as a stepper motor.
It is also known that the number of command pulses received can be utilized to signify the number of tracks across which the magnetic head must be moved in order to position the head at a desired track. Different systems, however, supply command pulses at different rates, and this has sometimes created a problem since many recording devices cannot respond at some command pulse rates and the rate of received command pulses can be such that optimum positioning of the heads is adversely affected.
In addition, acoustic noise arising in connection with movement of magnetic heads has also presented a problem, with such acoustic noise arising from exciting the resonance of the head moving apparatus sometimes causing severe problems, including possible damage to the head carriage mechanism.